Archive for October, 2006

There are many, many different ways of implementing consciousness, each with its own advantages and weaknesses, and it may well be that lots of them have been tried out during the course of evolution. So say Rodrick Wallace and Roger G. Wallace, in a paper(pdf) full of daunting mathematics and airy speculations.

The Wallaces take Bernard J Baars’ Global Workspace theory as their starting point. The Global Workspace theory sees consciousness as providing a general access function: a fleeting memory capacity that connects brain modules that otherwise function separately. It’s as though consciousness were a noticeboard where the different functions can post problems, warnings, discoveries and data which other functions may be able to use or respond to. Consciousness is there to provide an overall integrative function.

The Wallaces have developed a detailed analysis of the requirements of such a function, and they have come to the conclusion that many different architectures and organisations are capable of giving rise to something with the essential properties. Indeed, they see no barrier to a slow form of consciousness in all sorts of creatures: a kind of ‘paraconsciousness’, as they call it. The details of this notion are tantalisingly vague, but it seems the idea is that even trees might have processes which allow them a very slow and very dim kind of awareness. The Wallaces also see analogues of the Global Workspace in systems made up of multiple organisms: societies or ant colonies. The idea that such higher-level systems have at least some of the properties of consciousness is reminiscent of Ned Block’s ‘Chinese Nation’ thought experiment, in which the whole population of China is somehow dragooned into hand-simulating the nervous activity of a brain. The Chinese Nation idea, however, was supposed to demonstrate the weakness of functionalism by pointing out how absurd it is to think that this kind of gigantic hand-simulation of mental functions would give rise to anything like a mind. I suppose this perhaps shows how different our perceptions of intuitive plausibility can be.

The idea of higher level workspaces has a role, however, in overcoming some of the objections to the Wallace’s ideas. The most obvious objection, of course, is that they take the Global Workspace for granted: they say it is rapidly becoming the most favoured model among researchers, but even if that is true, it’s a long way short of being established. It remains quite possible that the theory is entirely wrong; or perhaps more likely, that an integrating function does exist, but does not constitute consciousness.

At the risk of being speciesist, it certainly looks as if the Wallaces are thinking of a form of consciousness somewhat short of the grand human version we are normally concerned with: they readily attribute it to a range of animals all the way down to cephalopods (who would surely achieve consciousness through a very different organisational structure from ours, given their tendency to rely on large neural ganglia distributed around the body rather than just a single central brain).

In fact the Wallaces are primarily interested in the palaeontology of consciousness, the road to which is, they say, wide and open (A rather optimistic conclusion, I think, since about the best evidence we can hope for is the shape of a fossil skull. The Wallaces’ own conclusions reinforce the common sense assumption that you can’t tell much about how a strange brain may have worked merely from its shape) . What strange forms of intellect may have flourished during the great Cambrian explosion, when many bizarre animals with strange body plans flourished!

However, they do have a view about the special qualities of purely human consciousness, and this is where the higher level workspaces come in. It is likely that all the different forms of consciousness tried out by evolution had different strengths and weaknesses: most would have suffered from some areas of ‘inattentional blindness’, but the creatures that had the smallest blind spots in the least important places would have survived best. Perhaps the unique trick of human consciousness, the one which fitted it for a distinctly human way of surviving, was to have a special facility for tuning in to higher-level workspaces: for fitting into complex societies and networks of communication and decision making.

This idea is more or less an aside in the Wallaces’ paper, but I can see some appeal in it, and I suspect it might in fact provide a more fruitful avenue to pursue than the attempt to reconstruct the minds of Acanthostega or Tulerpeton.

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This WordPress version is effectively the third incarnation of “Conscious Entities”, in succession to the original three-column model and the longer-running two-column one, both in non-compliant HTML. As yet, a number of recent posts and most recent comments are still missing, but that will gradually be sorted out over the next few weeks, as will any teething problems. Most of the pages from the previous (HTML) version will remain in place indefinitely, though some will eventually be superseded.

I’m sorry about any disruption and annoyance, but the change will save me time which should make for more and better posts, and it should also provide various enhancements to the site, notably an RSS feed.

Any feedback or comments, especially if there are problems, would be very welcome.

Peter

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Don’t look at I: me is doing all the work. To hell with grammar: that’s the point about consciousness, at least according to Tor Nørretranders. I must admit my heart sank just slightly when I first saw the title of his book The User Illusion. So many people want to denounce the self as an illusion these days! I think it’s actually rather hard to deny that my self has some real substance – for most purposes selfhood seems to be an inoffensive, if not essential means of distinguishing between matters bearing on one human animal rather than all the others. Some of the sceptical arguments certainly have their appeal, but I generally feel that the best of them question the nature, rather than the existence, of the self.

Be that as it may, Nørretranders puts together a good case. It has a strong central theme, though it draws on arguments from several different sources. It’s a wide-ranging book, in fact: in places it reminded me of Roger Penrose’s tendency to go off on fascinating but slightly peripheral expositions. There’s even a picture of a Turing machine, very similar to Penrose’s, with the infinite tape heaped up in lines of boxes which disappear over the horizon (I worry slightly about the tangles that are liable to arise here – wouldn’t it be better to have the tape hanging down into a bottomless void?)

The main perspective is of human beings as information processors, which means tackling the vexed question of what information really is and how it relates to reality. Nørretranders describes a conference where the participants boldly set out to get, as they put it “it from bit”, a fantastically optimistic aspiration. If, as Frege found, we can’t reduce maths to logic, how likely is it that we shall be able to reduce the actual existence of a particular apple to information?

Claude Shannon. of course, gave us a watertight way of doing hard calculations about information, but only by adopting a restricted definition, which relates it to order and entropy but excludes the whole idea of meaning, essential to the everyday conception of information. Quantifying information in this wider sense is formidably difficult. In ordinary human discourse, a few words can convey a tremendous quantity of information: in fact, in the right context a single symbol can speak volumes. An exclamation mark requires only a handful of bits, but when Victor Hugo and his publisher exchanged telegrams which read merely “?” and “!” a great deal was conveyed in both directions about the progress of Hugo’s latest book.

To me, such examples show that there is something fundamentally wrong with the wider quantification project: Shannon, I suspect, probably did about all that can be done. If I have agreed on a code or convention with my contact, a single exclamation mark can mean, not just many different things, but absolutely anything whatever: does that mean it conveys an infinite amount of information? In fact, Victor Hugo could go on deducing further information from his publisher’s message for an indefinite period: it told him, for example, that his publisher was still alive at the moment of composing the message: that he was alive a minute before that point, half a minute before that point, and… but you get the idea. The example may seem silly, but the problem is real.

Nørretranders takes a more optimistic view. Perhaps the real measure of information is not the content, but the work that had to be done to get that content; to whittle down the range of possible communications to the one we’ve chosen. In fact, and this is an idea which recurs throughout the rest of the book, perhaps the important thing is how much information we had to discard in arriving at our message. Nørretranders introduces the concept of exformation – all the extra contextual stuff which doesn’t get included explicitly in the message, but which the recipient can infer or recognise without difficulty. This is strikingly like the Gricean implicatures which Sperber and Wilson have tried to quantify, but that other line of enquiry into the same territory does not get discussed here.

A second broad theme concerns the limitations of consciousness: we think our conscious minds are in control, but in fact there is plenty of evidence that the bit of us that does the talking and writing doesn’t really do much else. Nørretranders quotes a wide range of evidence, mostly well-known to those of us who follow these things: blindsight, split brains, subliminal influences, the tendency of patients to produce a confabulated rationale for behaviour they weren’t actually in control of, and Libet’s finding that the brain is geared up to act before we have consciously decided on action. Nørretranders quotes a finding by Zimmerman that the maximum information flow of conscious sensory perception is a mere 40 bits per second, while the eye alone is sending ten million bits of information to the brain over the same period. All those millions of bits are surely there for some reason, but not, it seems, to support conscious decision making.

Nørretranders proposes a model in which the “me”, the unconscious mind, is working away with all the reams of information provided by the senses: when it needs to communicate with another me, most of the information is discarded, and the tiny remnant transmitted between the two “I”s, or the two conscious minds, of the parties involved: only a tiny amount of bandwidth is necessary: but the recipient’s “me” is able to recover the copious exformation which goes with the message. He suggests that the I is really similar in some respects to the “user illusion” which makes personal computers viable. We don’t need, and couldn’t cope, with knowing all the details of how our computer does what it does, how streams of digital numbers are moved around between specific locations in storage or various registers: instead we need a simple analogy with pieces of paper, wastebaskets, tools, and so on. The analogy can be pretty loose, or even downright misleading in certain respects, so long as it broadly conveys what is going on and reduces the formidable complexity of the actual processes to something we can manage.

I’m not sure that analogy is very precise. Generating an illusion of purposeful personhood seems a much more demanding business than making a complex computer process look like a simple real-life one. Who is the illusion for? Is it the unconscious me that is being fooled into thinking that there’s a conscious I in charge? How do you delude someone who isn’t conscious? Moreover, it’s surely I that think I exist, not me, so the illusion must actually be for I’s benefit: but if I’m illusory, how can I think anything, let alone fall victim to the illusion ofmy own existence?

It’s certainly true that a great many mental processes unfold unconsciously, but it’s far from clear that these unconscious processes fit together to form a coherent unconscious me. Nørretranders may have done himself a disservice by quoting so many exotic examples: the split brain cases suggest the unconscious me must be confined to one hemisphere of the brain, but the other cases, such as the blindsight ones, seem to contradict that. Most surprising of all in this respect is the way Nørretranders invokes and apparently endorses Julian Jaynes’ remarkable theory of the bicameral mind. According to Jaynes, we were actually not conscious until some point in ancient history: the part of our mind which we now perceive as our consciousness was previously interpreted as the voice of God or gods. But Jaynes has his preconscious people dealing with language readily: in fact the Aeneid is an example of the products of a bicameral mind (most implausibly, if you ask me, but still). That seems to fit very uneasily with an unconscious me which has run up the illusion of consciousness specifically in order to cope with language and other low-bandwith forms of communication.

It seems more likely that a whole series of unconscious processes are operating more or less separately. It also seems to me that the “I” as discussed by Nørretranders is drawn much too narrowly – it really amounts to no more than the part of us that does the talking. But I have had the experience, in stressful situations, of listening to my speaking part yak mindlessly on, while with my conscious mind I only wanted to shut up. When I play tennis, I don’t think in words about where to hit the ball, or even very explicitly in other ways: but to say my tactics were unconscious would be going much too far (even for me). I suspect a more accurate model of how things work would be a complicated mess of unconscious processes feeding into a conscious level which is itself complex, with different levels which are clearly distinguishable, though still operating essentially as a unity.

That said, Nørretranders gives an insightful account, and covers an awful lot of ground. I don’t know what me thought, but I enjoyed it.